I. Technical Field
This invention relates to a substrate processing method, a substrate processing apparatus, and a control program, and in particular to a substrate processing method and a substrate processing apparatus that do not produce watermarks on a substrate such as a semiconductor wafer after being cleaned, and a control program for automating substrate cleaning and substrate processing.
II. Description of the Related
Along with the recent trend of making semiconductor devices in finer dimensions, it is common practice to form various material films of different physical properties on the substrate. In particular in the Damascene wiring forming process in which the wiring grooves formed in the substrate are filled with metal, as extra metal is removed with the substrate polishing device (i.e. CMP:Chemical Mechanical Polishing) or wiring protection coat is formed by plating after completing Damascene wiring, films such as a metallic film, a barrier film, an insulation film, etc. of different wetting properties to water are coexistent on the substrate surface. In recent years, copper has come to be used as the wiring metal and the so-called low dielectric constant film (low-k film) has come to be used as the insulation film. Because of hydrophobic property of the low-k film, unevenness in wetting property of the substrate surface is on the increase.
The wet processes of the substrate such as CMP and plating, developing process, etching and cleaning process are always followed by cleaning, water removal, and drying. Unlike in the process of CMP or plating, in the cleaning process, the use of surface agent in order to forcibly adjust the surface wetting property is not desirable because of residual surface active agent on the substrate surface. However, when water removal and drying are made while uneven wetting property is left unchanged, water is first removed from part of low wetting property and liquid droplets remain on part of high wetting property. When the material of the latter part dissolve in the liquid droplets and dries, it finally produces water stain (watermarks). The watermarks may be problematic in reliability because they may cause leak or poor adhesion.
As the CMP or plating is mainly made by sheet-by-sheet process, it is also efficient to make the cleaning, water removal, and drying steps of the substrate in the sheet-by-sheet process (For example, refer to JP-U-H04-87638). For water removal and drying after cleaning using a sheet-by-sheet cleaning device, there are: a method of stepwise control of the substrate rotating speed in spin drying in which the substrate after cleaning is spun at high speeds to fling away water droplets, a method of spin drying in an inert gas atmosphere or under reduced pressures, and a method of producing Marangoni convection effect by supplying isopropyl alcohol (IPA) vapor or the like during drying. These methods are intended to suppress the occurrence of watermarks.